Measuring and controlling system



March 29, 1938. J. D. RYDER 2,112,682

MEASURING AND CONTROLLING SYSTEM Filed June 24, 1935 5 Sheets-Sheet 1 Ell AC 0 no 5 7 INvENroR. JOHN 0. P705? 2 Y M 47" M W.-

March 29, 1938. J, RYDER 2,112,682

MEASURING AND CONTROLLING SYSTEM Filed June 24, 1955 3 Sheets-Sheet 2 AC0: 0 C.

INV ENT OR.

Jamv D. FY00? March 29, 1938. J RYDER 2,112,682

MEASURING AND CONTROLLING SYSTEM Filed June 24, 1955 3 Sheets-Sheet 3 STEAM fZon/ fie. 9

INVENTOR.

JOHN D. Prat-R Patented Mar. 29, 1938 ,UNITED STATES MEASURING AND CONTROLLING SYSTEM John D. Ryder, South Euclid, Ohio, asslgnor to Bailey Motor Company, a corporation of Delaware Application June 24, 1935, Serial No. 28,219

8 Claims.

This invention relates to the art of measuring and/or controlling the magnitude of a variable quality, quantity, condition, relation, etc, and particularly such variables as temperature, pressure, rate of fluid flow, etc... although the variable may be of any physical, chemical, electrical, hydraulic, thermal, or other nature or characteris tic.

In accordance with my invention I cause the effective area of an electrode of an electron dis charge device to be varied proportional to the instantaneous magnitude of the condition or var iable to be measured and then by a suitable measuring circuit, 01! which the electron discharge device is a part, I determine the magnitude of the variable, or obtain a measurement or movement representative of such ma itude.

Such measurement or movement may then be utilized in the control of the same or other var iable or variables.

A primary object of my invention is to provide a measuring apparatus capable of exhibiting variations in the actual magnitude of a condition or variable substantially instantaneously with the occurrence of such variation and so that an observer will be advised of the magnitude of the condition at any time existing and not of the magnitude which existed at some time previously, except insofar as such condition might be re corded for permanent record. In other words, to avoid a time delay between the occurrence of a change in magnitude and the presentation of such change for observation upon a measuring instrument or as applied to control apparatus.

A desirable feature of the invention is that the said measurement or movement may be ampliiied many times and may be transmitted to a point remote relative to the variable to which the apparatus is sensitive.

An important object of the invention is the inclusion of an anti-hunting means tending to allow maximum speed of control with a minimum of over-travel or hunting.

A further object is to so arrange the control circuit that control of either a floating or positioning characteristic may be obtained.

My invention will be best understood by when ence to the accompanying drawings in which I have shown preferred embodiments thereof and which will be described hereinafter. I desire to have it understood however that various changes can be made in the construction and arrangement of the parts without departing from the spirit and scope of the invention.

.In the drawings:

Fig. 1 is a diagram illustrating an embodiment of the invention. I F1Figl. 2 shows a modification of a fragment of Fig. 3 is similar to Fig. 1 with some modiflca- 5 tions. Fig. 4 illustrates a second embodiment of my invention.

Figs. 5, 6, 7, and 8 show modifications of the arrangement at Fig. i. g 0

Fig. 9 illustrates a modification.

Fig. 10 shows a further embodiment of the in= vention.

Referring now in particular to Fig. 1, I therein illustrate my improved measuring apparatus and 15 electrical circuit in connection with the remote indication of a fluid pressure. The conduit 0 may be adapted to contain a static or flowing fluid, the pressure of which is desirably to be remotely measured for visual indication or as a guide to 0 the control of the pressure or another variable.

Sensitive to the fluid pressure is a Bourdon tube it, from the free end of which is suspended a link 3 carrying at its lower end the plunger 4 of a solenoid. The link 3 is pivotally connected to 25 move an element 5: passing through and fastened to a thin metal diaphragm i5 forming an end closure of an electron discharge device l.

The electron discharge device '21 is preferably a Z-element tube having a movable anode 8 and so a heated cathode The envelope, of which the diaphragm. t forms part, may be oi metal or of glass, but preferably of such shape and construction that the diaphragm 6 will flex to allow movement of anode 3 within the envelope to as a result of positioning the member 5 through means external to the envelope, such as the Bourdon tube 3.

Such an electron discharge device or tube is preferably a high vacuum tube of the regulating 40 type, wherein the effective electron emitting or electron receiving areas of the electrodes are varied without necessarily changing the distance between the electrodes. As shown in the drawings, movement of the anode 8 relative to the 46 cathode 9 causes a change in magnitude or the electric current which flows through the tube, and while the tube is not of the stop-start gridcontrol type, nevertheless movement of the anode away from the cathode in sufficient extent may 50 reduce the current passage to zero.

There is normally a current flow from the A. C. or D. C. source It, through the anode 8. cathode 9, and resistor H; varied in quantity by the position of the anode relative to the cath- 55 ode. Such current flowproduces a voltage drop across the resistor II, which is applied to the input circuit of a multi-electrode grid-controlled electron discharge device l2 having an anode II, a grid I4, and a cathode l5. Such a tube is preferably a relay and amplifying tube and is shown as of a heated filament type.

The circuit is such that the grid I4 is negative relative to the cathode I! in varying amounts, dependent upon the voltage drop across the resistor l l, thereby giving control of current passage through the tube l2.

Current flow through. the tube 1 representative of position of the Bourdon tube 2 thus controls voltage drop across the resistor II which in turn controls current flow though the tube l2. The circuit including the tube" I2 may be traced as follows: source I0, resistor ll, cathode l5, anode l3, ammeter l6, solenoid coil i1, and source Ill.

The ammeter l6 may be located remotely and provides a visual indication of fluid pressure within the conduit I. Current flow through the solenoid winding l1 produces a varying eifect upon the core 4 to oppose movement of the Bourdon tube and balance the same. The inclusion in the arrangement of the solenoid 4, H for opposing movement of the Bourdon tube 2 tends to eliminate error producing effects of tube characteristics and voltage variations throughout the circuit, and has the further advantage that the Bourdon tube need not be accurately calibrated, for it does not have to assume a position definitely indicative of pressure but each time returns almost to the original position. The system comes to a state of equilibrium regardless of the position of rest of the free end of the Bourdon tube and when such state of equilibrium between pressure of the fluid within the Bourdon tube and pull on the solenoid 4 is accomplished, then the current flow through the ammeter i6 causing the pull on 4, is a measure of the fluid pressure.

At Fig. 2 the element 5 may be positioned through movement of the free end of a bimetallic member l8 sensitive to ambient temperature.

At Fig. 3 I show a circuit similar to that of Fig. 1 except that the solenoid 4, I1 is replaced by a heater element iii, the coil of which receives the current of the ammeter circuit in a manner similar to the coil ll of Fig. l. The link 3A at its upper end is connected to the Bourdon tube or other variable sensitive device for positioning the same. Normally the link 3A positions the member 5 as in Fig. 1, but such positioning is opposed or modified by a bimetallic thermostatic element 20 tending to correct for variations in ambient temperature. Current flow through the circuit 01 the indicating device l6 passes through the coil is heating the thermostatic element H for producing a force or movement opposing and balancing that of the link 3A in a manner similar to the solenoid 4, l! of Fig. 1.

The arrangement of-Fig. 4 provides a torque amplifier without electrical contacts. It is suitable for use as a controller, since it provides a ready means of running a reversing and variable speed motor in either direction upon a change in the value of the variable, and the motor will run at a speed proportional to the change if an induction motor is used.

I show at 22 a motor having opposed field windings 23, 24 connected in an alternating current circuit and opposedly wound in a manner such that when the windings 23 and 24 are equally energized a rotor 25 is not urged to rotation in either direction; but when the windings are unequally energized rotation of the rotor 25 will occur in predetermined direction and at a speed dependent upon the unbalance of the energization of the windings.

The rotor 25 is connected by means of suitable gearing 26 to position a regulating valve 21 controlling fluid pressure within the conduit I, and at the same time to position a rack 22 connected to the tube 1 for positioning the same. The rack 28 carries a pointer 23, relative to an index 32. for providing a visual indication of fluid pressure within the conduit l.

The held windings 22, 24 are connected-in parallel across an alternating current power source 3!; and differentially in the primary circuit of transformers 22, 22 respectively; the current flow for energization of 23, 24 being controlled by varying the impedance of the primaries upon variation in the current flow through the related secondaries. The secondaries are connected respectively in circuit with electron discharge devices 34, 35 and the arrangement is such that if one of the devices 34, 35 is passing current and the other is not passing current, then one of the field coils 23, 24 is energized and the other is de-energized, so that the rotor 25 is caused to rotate continuously at maximum speed in a given direction. If however both the devices 34, 25 are passing curi'ent in equal amounts then the field windings 23, 24 are energized in equal amounts and the rotor 25 is not urged to rotation in either direction. The latter is a condition which exists when pressure within the Bourdon tube 2 is steady and does not vary from a previous condition. Immediately upon a variation or change in the pressure, however, the conditions become unbalanced to an extent wherein one of the field coils 23, 24 is energized to a greater extent than the other and the rotor 25 is caused to rotate in predetermined direction, and at a speed dependent upon the amount of unbalance of the field coil energization.

The output of the devices 34, 35 is controlled by a circuit including the grids respectively of the devices, as well as the tube 1, whose anode is positioned relative to its cathode by movements of the Bourdon tube 2.

Certain features of the electrical circuit of Fig. 4 are disclosed and claimed in my co-pending application, Serial No. 718,427, filed March 31, 1934. A voltage divider 36 as well as resistances 31, 38 are provided in the control circuit of the devices 34, 35. If there is no current flow through the tube 1, the electron discharge device 35 passes current and the device 34 does not. When a maximum current flows through the tube 1 then the device 34 passes current but the device 35 does not. At all intermediate values of current flow through the tube 1 the twodevices 34, 35 pass proportionate amounts of current and proportionally or differentially vary the impedance of the secondaries of transformers 32, 33, resulting in a corresponding variation in energization of the field windings 23, 24, and if the energization of the windings is unbalanced, then rotation of the rotor 25 is in predetermined direction and at a predetermined speed dependent upon the amount of unbalance.

It will be observed that when the anode of the tube I is in a predetermined position relative to the cathode there will exist a condition of equal current flow through the primaries of the transformers 32, 33, through the secondaries, and through the windings 23, 24 of the motor 22, and that the rotor 25 will not be urged to rotate in either direction. Immediately upon a change in fluid pressure eilective upon the Bourdon tube 2, the anode of the tube 1 will be moved relative to its cathode, thus increasing or decreasing the current flow through the tube I and unbalancing the current flow through the devices 34, 35 and correspondingly through the fleid windings 22, 24 sothat the rotor 25 will becaused to rotate in predetermined direction and at a speed dependent upon the amount 01' movement of the Bourdon tube 2.

Such rotation of the rotor 2! will be in direc tion to position the valve 2! for correcting the value of the fluid. pressure, or tending to return the pressure to a predetermined value. Simultaneously the rack 28 will be moved in a direction to reposition the anode-cathode relation through movement of the entire tube 1 relative to the Bourdon tube 2." As such'movement progresses, the currentyflowthrcugh the tube is returned toward its predetermined value, thus slowing down rotationoi' the motor 22 until eventually the fields. become balanced and the rotor stops moving. The Bourdon-tube itself assumes at all times a position representative of fluid pressure, as does the pointer 29 relative to the index 30, from the interrelation of which may be visually observed the value of the fluid pressure.

Such a control as I- have described for Fig. l is known as a positioning" control where there is a. definite position of the valve 21 corresponding to every value of the fluid pressure. At Fig. 5 I illustrate a modification wherein there is no tie-back such as the rack 28 for movement oi" the tube 1, and this is known as a floating" control wherein there is no definite positioning of the valve 21 for each value of fluid pressure within the conduit. Herein the pointer iii is positioned relative to the index 30 directly by the Bourdon tube. The motor 22 is geared through suitable reduction means to position the valve 2i.

At Fig. 6 I illustrate an arrangement similar to that of Fig. 4 wherein that part of the circuit on the drawings to the right of the points X, Y is identical with the showing of Fig. 4, but that part to the left illustrates an arrangement for combining the effect of a plurality of variable conditions upon the motor 22 differentially or additively. I illustrate three tubes '5, l, "5, connected in parallel in a manner such that the current flow applied to the right-hand part oi the circuit at the points X, Y is the sum of the separate current flows of the three tubes, each representative of the value of the variable adapted to mechanically position its anode.

For example, this might be used in the control of the supply of water fed to a steam generating boiler wherein the motor 22 would. be adapted to position a water regulating valve and from an interrelation of a measure of steam flow from the boiler, a measure of water flow to the boiler, and a measure of water level within the boiler.

At Fig. '7 the tubes l, 1', 'l", are connected in series. At Fig. 8 they are connected in parallel as in Fig. 6 but additionally show at 353, ill, ll means for varying the sensitivity of the different devices, or in other words varying upon the motor 22, the relative effect of the plurality of variable conditions such as steam flow, water flow, water level.

At Fig. 9 I illustrate a portion of the circuit.

wherein variations in current flow applied at X, Y for control of current flow through the tube i2 causes a vertical positioning of a pilot valve 2, spring opposed, for control of air pressure which may be used in pneumatic control apparatus or arrangement. Such a pilot valve may be of the type described and claimed in the cc-pending application oi Clarence Johnson #673,212, filed May 27, 1933, Patent No. 2,054,464, September 15, 1936, and wherein vertical positioning of the pilot valve stem 42 results in a variation in fluid pressure in either or both of the pipes leading from the pilot valve casing.

At Fig. 10 I illustrate an embodiment 01' my invention wherein the motor 43 is not of the reversing type but rotates in a single direction at a speed which is a function-oi the variable actuating the tube 1 from zero to a maximum speed. Such a motor may be a draitian driving motor or a pump motor, or similar device, whose speed is desirably to be controlledfrom the value of a variable such as an operating condition in a fur nace. orfor the control of a'variable.

The tube i contro1sthe phase or the voltage on the grid of tube 54 through the transformer lil. This varies the current flow' through tube 44 and thereby. the speed of motor 43. An important feature is that the conductors 46 41 may be made practically any length of telephone lines, thereby achieving control of a variable at a great distance. Variation in current flow through the secondary S of the transformer varies the current flow through the primary P as well as the phase angle, for with no current flow through S the current through P is practically 90 degrees lagsing with. respect to voltage. This turns off thetube 14. The primary P and a resistance 48 are in shunt around the tube 44 and voltage across it is 90 degrees lagging with respect to voltage across the tube 44, which thus turns the tube oil. With maximum current through S the primary current is practically in phase with the voltage and the grid voltage is the same, resulting in maximum current flow through the tube 44. Thus variation in voltage drop across 48, as well as phase relation, controls current flow through the tube M and thereby through the motor 43 for controlling the speed of the motor 43.

While I have illustrated and described certain preferred embodiments of my invention, it will be clear that there are other ways of incorporating the invention in apparatus and electrical circuits and. i am not to be limited by the particular showing, but only as to the claims in view of prior art.

Certain features of my invention disclosed but not claimed herein form the subject matter of my co-pencling application Serial No. 191,059, riled February 17, lEi3Ei.

What I claim as new, and desire to secure by L tters Patent cf the United States, is:

l. a measuring arrangement, in combination, means positioned by a variable to be measured, an electric circuit, an electron discharge device in said circuit and having a plurality of electrodes, said means adapted to change the effective area of one of the electrodes, a. plurality of other electron discharge devices in the circuit, and a motor having'opposed fields in the circuit, current flow through said first device differentially controlling said plurality of devices for varying the relative energization of said opposed fields.

2. A measuring and controlling system, comprising in combination, means positioned by a variable to be measured and controlled, an electric circuit, an electron discharge device in said circuit and having a plurality of electrodes, said means adapted to change the effective area of fill one 01' the electrodes, a plurality of other electron discharge devices in the circuit, a motor having opposed fields in the circuit, current flow through said first device difierentially controlling said plurality of devices and varying the relative energization of said opposed fields, an indicator of the value of the variable positioned by the motor, and regulating means for the variable simultaneously positioned by the motor.

3. In combination, means sensitive to the magnitude of a variable, an electron discharge device having relatively movable electrodes for varying their effective areas whereby the resistance of said device to passage of current is varied, means under the control of said first named means for moving one of said elements, a plurality of electron discharge devices, means controlled by the current passed by said first electron discharge device for controlling said plurality of electron discharge devices to produce concurrent variations in opposite senses in the current in their output circuits, a motor having opposed fields, the current in each field under the control of the current in one of said output circuits, and means for moving the other of said electrodes of said first named electron discharge device un der the control of said motor.

4. In combination, means sensitive to the magnitude of a variable, an electron discharge device having relatively movable electrodes for varying their effective areas whereby the resistance of said device to passage of current is varied, means under the control of said first named means for moving one of said elements, a plurality of electron discharge devices, means controlled by the current passed by said first electron discharge device for controlling said plurality of electron discharge devices to produce concurrent variations in opposite sense to the current in their output circuits, a motor having opposed windings, the current in each winding under the control of the current in one of said output circuits, and means for moving the other of said electrodes of said first named electron discharge device under the control of said motor.

5. In combination, means sensitive to the magnitude of a variable, an electron discharge ice-ice having relatively movable electrodes for varying their effective areas whereby the resistance of said device to passage of current is varied, means under the control of said first named means for moving one of said elements, a plurality of electron discharge devices, means controlled by the current passed by said first electron discharge device for controlling said plurality oi electron discharge devices to produce concurrent variations in opposite senses in the current in their output circuits, and a motor having opposed windings, the current in each winding under the control of the current in one of said output circuits.

nitude of a variable, an electron discharge device having relatively movable electrodes for varying their eiiective areas whereby the resistance of said device to passage of current is varied, means under the control of said first named means for moving one of said elements, a motor having opposed windings, and means under the control of the current passed by said first electron discharge device for producing. concurrent variations in opposite sense of the current in said windings.

7. In combination, means sensitive to the magnitude of a variable, an electron discharge device having relatively movable electrodes for varying their effective areas whereby the resistance of said device to passage of current is varied, means under the control of said first named means for moving one of said elements, an electric circuit having a plurality of branches in parallel and means under the control of the current passed by said first electron discharge device for producing concurrent variations in opposite senses of the currents in said branches.

8. In combination, means sensitive to the magnitude of a variable, an electron discharge device having relatively movable electrodes for varying their efiective areas whereby the resistance of said device to passage of current is varied, means under the control of said first named means for moving one of said elements, a plurality of electron discharge devices, means controlled by the current passed by said first electron discharge device for controlling said plurality of electron discharge devices to produce concurrent variations in opposite senses in the current in their output circuits, a motor having opposed windings, a circuit for each of said windings and an inductive coupling between each of said last named circuits and the output circuit of one of said plurality of electron discharge devices.

JOHN D. RYDER.

6. In combination, means sensitive to the mag- 

